Construction and method of operating dynamo-electric machines



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I F. H. LOVERIDGE. GONSTRUGTION AND METHOD OF OPE-RATING DYNAMO ELECTRIC MACHINES.

No. 544,361. Patented Aug. 13, 1895.

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1:". H. LOVERIDGE.

CONSTRUCTION AND METHOD OF OPERATING DYNAMO ELECTRIC MAGHINESRR No. 544,361. Patented Aug. 13, 1895.

MM H M A A Wwvzgyg (No Model.) 3 Sheets-Sheet 3. F. H. LOVERIDGE. CONSTRUCTION AND METHOD OF OPERATING DYNAMO ELECTRIC MACHINESJ= No. 544,361. Patented Aug. 13, 1895.

UNITED STATES PATENT GFFTQEQ FREDERICK I-I. LOVERIDGE, OF COLDWATER, MICHIGAN.

CONSTRUCTION AND METHOD OF OPERATING DYNAMO-ELECIRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 544,361, dated August 13, 1895.

Application filed August 2, 1894:. Serial No. 519,259. (No modelfi To all whom it may concern.-

Be it known that 1, FREDERICK H. Levan- IDGE, a citizen of the United States, residing at Goldwater, in the county of Branch and State of Michigan, have invented a certain new and useful Improvement in the Construction and Method of Operating Dynamo-Electric Machines, (Case No. 1,) of which the following is a full, clear, concise, and exact description, reference being bad to the accompanying drawings, forming a part of this specification.

In the operation of dynamo-electric machines for supplying translating devicesas, for example, are lamps placed in serieswith electrical energy one machine has been required for each circuit. IVhen the number of translating devices has been changed, as

. by cutting in or cutting out lamps, it has been common to adjust the brushes about the commutator to vary the electromotive force, as the resistance of the circuit is thus changed, for the purpose of maintaining the normal current strength under such changes in load or circuit resistance. The brushes consist usually of flat strips of copper, sometimes slotted like a comb at their free ends, or of copper wires laid up together, or they may be of carbon, and only a single pair of such brushes have been ordinarily used upon the commutator of a machine, and they have been placed diametrically opposite one another. Each member of such a pair of brushes may consist of a single brush such as I have indicated. The brushes must each have a certain collecting area or overlap upon the commutator. This is required in order that there may be sparkless commutation.

With machines having a uniform commntating field-that is, machines in which each coil of the armature cuts the same numberof lines of force during commutation-this collecting area or overlap should be of a definite amount, whether the brushes are well forward,as in the case of light load, or well back toward the position of maximum difference of potential, as when the machine is running under full load. In certain machines not having such uniformity of field provision is made for varying the overlap or collecting area of the brushes, in which case each of the positive and negative brushes consists of two parts or members, and the members of each brush-that is, the two parts of each com pound brush-are adapted to be adjusted so as to vary their collecting area or overlap. By such setting or adjustment of the brushes the field of force can be made effectively uniformthat is, so that each coil when under a brush will during such time-thatis, while short-circuited and undergoing the process of commutationcut the propernumberof lines of force.

Heretofore it has been common with machines ad'apted'for brushes with a fixed overlap to simply rotate the yoke or brush carrier forward andbackward, the two brushes being maintained in the same position relatively to one another, and this practice has obtained with machines having a single set of fieldpoles, as well as with machines having two or more sets of such poles.

lhe positive and negative brushes have been maintained diametrically opposite with non-uniform field-machines as well as with those having a uniform field which do not require or admit of variation in the overlap of the brushes. I have discovered that the brushes may be placed in any convenient position under the pole-pieces, and that as long as the normal current is maintained the commutation will be effected without injurious sparkingthat is to say, one brush of a pair having a proper overlap may be set at random under its proper pole-piece and maintained in that positioinwhile the other brush may be moved at random under its polepieceand so long as the normal current flows through the armature sparkless commutation will take place-that is to say, the brushes may be set at random, and so long as the proper current is maintained through the machine sparkless commutation will take place. In case the dynamo is provided with two or more pairs of pole-pieces several pairs of brushes may be employed and as many independent circuits supplied from one machine for example, a machine with four poles-that is, with two pairs of pole-pieces-may be provided with two sets of brushes. The two brushes of each pair will be placed under adjacent pole-pieces of opposite sign, and one brush of each pair having the same sign may be maintained in a fixed position under its own pole-piece. It is desirable that the fixed brushes should be symmetrically disposed with respect to their pole-pieces, and the fixed brushes are preferably connected by a conductor of low resistance. This connection I do not consider necessary, though it seems desirable.

In the case of a machine having three sets of pole-pieces and provided with three pairs of brushes, the fixed brushes-that is, one of each pair of the same signwould be disposed similarly, as in the case of two pairs of brushes, and preferably joined by a low-resistance connection.

My invention herein is specially intended to be applied to machines having their armatures provided with a single set of coils adapted for serious work. In such machines the armature, looked at from an instantaneous point of view, may be considered as consisting of as manydefinite fractional portions as there are individual magnetizing forces constituting the field of force.

Speaking generally, my invention consists in a new art of operating dynamo-electric machines, whereby as many separate and independent circuitsmay be supplied from the same machine as the machine has pairs of pole-pieces. I contemplate adjusting but one member of each pair of brushes. For exan1- ple, I have discovered that with an ordinary bipolar machine either brush may be placed at any suitable position under its pole-piece and there maintained without adjustment, all the adjustments for current regulation being made by rotating the other brush of the pair within the arc of its pole-piece-that is to say, what has been termed the diameter of commutation may become a line, which does not pass through the center of the circumference, or, geometrically speaking, the diameter of commutation may become the chord of commutation.

When in the case of bipolar machines the brushes are not placed diametrically opposite, the two branches or sides of the multiple-arc circuit between said brushes, including the coils of the armature, will not be equal-that is to say, the coils of the armature will not be of the same number in each of the two branches, and in such case, as is well known, the entire resistance between the brushes will be less than when the brushes are placed diametrically opposite, so as to evenly distribute the coils between the twolimbs or sides of the multiple-arc circuit. The same rule applies when two or more independent circuits are taken o'tf from the same machine and one set of brushes of the same sign connected together by an equalizer-that is to say,the resistance offered by the armature to the current of any circuit will be greatest when an independent brush is placed midway between adjacent brushes that are connected by an equalizer, and when such brush is adjusted or moved from such middle position, as is contemplated by myinvention herein, the resistance will be correspondingly reduced. From this it follows that by the use of my invention an armature havinga given winding will have a greater efficiency when the brushes are not diametrically opposite, or when the internal resistance of the armature between the brushes is diminished by an analogous disposition of the brushes, as illustrated and described herein. Moreover, there is an economic advantage in the construction, operation, and maintenance of one large dynamoelectric machine having a large aggregate electrical energy as compared with the construction and maintenance of several small machines capable of developing alike amount of energy.

By the application of my invention a dynamo-electric machine may be made to supply electrical energy to two or more circuits, each or any of which may include avariable number of translating devices connected in series, any one of which translating devices may require for normal operation a varying amount of energy. Any variation of the conditions necessary for the operation of the translating devices, as are lamps or motors in one circuit, will have no detrimental influence on the ctli-- ciency of operation of the translating devices in the remaining circuit or circuits.

To state it in another way, it is an object of my present invention to provide meanswhereby two or more circuits, any or all of which containing a varying number of translatin devices connected in series, may be elhciently supplied with electrical energy generated by a single dynamo-electric machine. l-Ieretofore, so far as I know or am informed, this object has not been attained in any degree for practical purposes. In series are lighting, for example, it has often been desired to supply a very large number of lamps with energy from a single dynamoanachine, but the practical limit has been about five thousand volts, since one dynamo could only supply a single circuit of lamps connected in series and arranged to be operated by a curreutofconstai'itvalue. Accordinglythenumber of lampsthat it has been found practicable to supply by one dynamo-electric machine has been limited by the maximum electromotive force which might be prudently used in connection with one circuit. Someof the most skilled and experienced in municipal electric lighting object to a circuit being supplied with current at a higher pressure than twenty-five hundred volts. Thus, if the number of lamps required to be operated is very great, the number of machines must be increased accordinglythat is, oneseparate machine for every fifty or hundred lamps requiring the ordinary voltage.

The separate circuits which may be supplied from a single machine of my invention may be of any desired pressure, the limits being only the limits that are to be determined by practice.

To show a phase of the application of my ICC invention I would mention that a machine constructed for supplying two or more circuits may utilize one or more of these circuits as a motor-circuit or as motor-circuits to drive the armature, the remainder being used in the ordinary way.

My invention will be more readily understood by reference to the accompanying drawings, in which- Figure 1 is a view illustrative of a bipolar machine equipped with a single pair of brushes in connection with a regulator for automatically adjusting one of the brushes to maintain the current under changes in load. Fig. 2 is a view illustrative of some of the details of a multipolar machine adapted to be employed to supply independent circuits, the pole-pieces being specially cut for subdivision of the field of force. Fig. 3 is a diagram illustrative of a four-pole machine equipped with two pairs of brushes and supplying two independent lamp-circuits in accordance with my invention. Fig. 4 is a View of the same machine, showing one of the circuits equipped as a motor-circuit to drive the armature while the other circuit is supplying a load of lamps. Fig. 5 is a view illustrative of amachine having three pairs of unequal pole-pieces, each pair of pole-pieces. having a corresponding pair of brushes, each pair of brushes being connected with a separate circuit, the capacities of the circuits being different and dependingupon the magnetic capacity of their respective pole-pieces. Fig. 6 illustrates a machine having eight field pole-pieces and adapted to supply four independent circuits of substantially equal capacity, since the pole-pieces are uniform.

Referring now to Fig. 1, itwill be seen that the two brushes a a are placed respectively under the opposite pole-pieces. The brush a may be considered as fixed in position, while the brush a is adapted to be rotated by means of the regulator a This automatic regulator may be of any usual construction. I have employed successfully that form known as the Scribner regulator and shown in United States Letters Patent No. 435,526, granted September 2, 1890, for regulator for dynamoelectric machines. This current-regulator consists of a driven motor, which is controlled by an electromagnet placed in the circuit of the machine. In case only one brush is moved its range of movement must be sufficient to change the electromotive force the amount requiredthat is, the single brush must be moved a distance equal to something like the sum of the movements of the two brushes when both are rotated. The adjustment is therefore made more delicate, and any irregularities in the movement of one brush will create less disturbance than when both brushes are moved through the same distance.

I have, as shown in Fig. 2, specially constructed the pole-pieces. Thus I prefer to slot or otherwise subdivide each pole-piece in order that the field of force produced thereby .use of separate armature-windings.

may be more properly distributed. In this instance the pole-piece shown in Fig. 2 is provided with the slots 1) b 12 The particular machine shown in Fig. 2 is assumed to have one hundred and sixty segments upon the commutator. pair is mounted on an independently-rotatable arm. The brush b is mounted upon the arm I). The adjustable brush of the other pair (not shown in the drawings) is mounted upon a similar arm b The brushes which do not require adjustment and which. are not shown may be considered as mounted on arms b N, respectively.

In Fig. 3 I have shown two lamp-circuits. The circuit is shown passing through the coils of the field-magnets, while the circuit at is shown simply passing from one brush through its series of lamps and thence back to the other brush of its pair. My experiments indicate that the arrangement of the circuits so that one of the independent circuits shall. include the coils of the field-magnets is preferable to including a portion of the coils of the field-magnets in each or part of the independent circuits. The brush 6 may be adjusted either manually or automatically, as described, to maintain the current in circuit a of the desired value under changes of circuit-resistance. In like manner the brush f may be adjusted in accordance with the load of circuit d. The brushes g g are assumed to remain in a practicallyfixed position under their pole pieces, respectively. Brush 9 may be referred to as one of the pair belonging to the circuit 0, and brush g maybe referred to as one of the pair belonging to the circuit (1; yet as these brushes 9 g are preferably connected by the low-re sistance equalizer g they may be considered in connection with the equalizer as forming one of the terminals of each of the independent circuits-that is to say, there is a general or common terminal connection for each of the independent circuits formed by the fixed brushes electrically united. When the equalizing connection g is omitted, the pair of brushes 6 9 may be considered as independent of the pair of brushes f g-that is, each pair may be used as the terminals of a separate circuit. I have not as yet definitely determined the special utility of the equalizing connection, though my experiments indicate that the operation of the machine is improved by the use of the equalizer when the fixed brushes are placed in position to have the same potentialthat is, in machines having four equal poles when the fixed brushes are placed diametrically opposite.

In Fig. 4 the same machine illustrated in Fig. 3 is shown connected as a motor-dynamo. By motor-dynamo I mean the same machine adapted to be driven as va motor and at the same time to generate energy for supplying one or more independent circuits without the The circuit it corresponds to circuit 0 of Fig. 3, and

The movable brush of each a 54.4,sei

the circuits (1 of Figs. 3 and l are the same, except that in Fig. 4, there being more lamps in circuit, the brushf will be adjusted bacl ward farther than is indicated in Fig. 3. The circuit 7L, instead of being provided with translating devices, as is the corresponding circuit 0 of Fig. 3, is supplied with current from an independent generator hthat is, the generator 72/ sends current over circuit 71. in a direction to drive the armature of the same machine as a motor. The field-coils I have shown included in the circuit h. This arrangement of circuits I believe the best, though other arrangements obviously might be utilized.

In Fig. 5 I have shown a machine provided with three sets of unequal pole-pieces and three corresponding sets of brushes, each set or pair of brushes belonging to a separate and distinct circuit, which circuits 2' 2" t corresponding to their pole-pieces, respectively, are as to capacity unequal. The brushes are adjusted to fall under their respective poles. The movable brushes 7c 7.; of each set may be controlled and adjusted as described with respect to brush a of Fig. 1 to maintain the current constant under changes of load. The brushes Z Z -1 having been brought to their proper positions, are not further adjusted. The output of the entire machine is not equally divided between the several circuits. The brushes Z Z Z are shown united by the low-resistance equalizing connection.

The machine shown in Fig. 6 is provided with four sets of equal pole-pieces, and the four sets of brushes are arranged under the pole-pieces. The movable brushes m m m m (being of the same sign) are adapted to be adjusted in accordance with the loads of their circuits, respectively, while the remaining brushes n n n n are ordinarily left under their respective poles without adjustment.

I have thus shown that my invention is specially designed to be applied to systems in which electric lamps or other translating devices are connected in series, and that in such systems almost any desired number of inde pendent circuits may be supplied with the amount of energy that may be desired from the same machine.

My invention, in so far as the same relates to supplying two independent. circuits from the same machine, may be utilized in connection with any multipolar arc-light dynamo. In case the machine should not be provided with a properly-distributed field of force some accessory device must be employed, in order that the field may be effectively uniform-as, for example, by employing, instead of single brushes, sets of brushes in which the individual members consist of two parts, so that the overlap may be adjusted either automatically or otherwise.

My invention may be applied to the construction of machines of a given voltage that shall have any desired capacity in. lamps, and, on the other hand, having a given number of lamps or translating devices to supply, it is practicable to employ the invention to construct machines that will have as low voltage as may be desired.

In a multipolar machine the different sets of field-poles, which are next to one another, act to produce lines of force which are cut by the armature-coils as the armature rotates. The different circuits are connected in the manner described, so that primarily the energy which is developed in the armature from a particular set of pole-pieces is sent out in the form of current over a particular one of the independent circuitsthat is, speaking generally, it may be said that each set of pole-pieces acts individually, so to speak, and produces a field, which field, by means of the rotating armature, develops current which is directed to a particular circuit. It is true that each set of pole-pieces will have a certain influence upon the entire field of the machine, because they all include the armature in their magnetic circuits. The influence, however, of one set of field poles upon the armature-coils, when not directly within the influence of said set, may be looked upon as a necessary incident to the mode of operation of the machine, and the fact remains, as stated above, that primarily the energy from one set of field-poles is transferred to a particular circuit.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The combination with a dynamo electric machine having two or more sets of pole pieces, of pairs of brushes and independent circuits equal in number to the sets of pole pieces, the separate brushes forming the pairs of brushes constituting the terminals of the different circuits, respectively, being placed under adjacent pole pieces of dilferent signs,

and one brush of each pair being adapted to be adjusted, the adjustable brushes of the ditferent pairs being all of the same sign, whereby the currents of the different circuits may be regulated and maintained each at the desired value, substantially as and for the purpose specified.

2. The combination with a dynamo electric machine having two or more sets of pole pieces, of pairs of brushes and independent circuits equal in number to the sets of pole pieces, the separate brushes forming the pairs of brushes constituting the terminals of the diiferent circuits, respectively, being placed under adjacent pole pieces of different signs, and one brush of each pair being adapted to be adjusted, the adjustable brushes of the different pairs being all of the same sign, and the fixed brushes of the different pairs being connected by an equalizer.

3. The combination with a dynamo electric machine having two or more sets of pole pieces, of pairs of brushes and independent circuits equal in number to the sets of pole pieces, the separate brushes forming the pairs of brushes constituting the terminals of the different circuits, respectively, being placed of under adjacent pole pieces of different signs,

a id one brush of each pair being adapted to be adjusted, the adjustable brushes of the different pairs being all of the same sign,and the fixed brushes of the different pairs being connected by an equalizer, the said fixed brushes thus connected being placed at positions of practically equal potential.

4:. The method of operating dynamo electric machines, which consists in subjecting the armature coils to individual magnetizing forces constituting the field, and utilizing the electrical energy developed in different definite fractional parts of the armature by the individual forces to supply different and independent circuits, each independent circuit being supplied with energy from a particular one of said individual magnetizing forces, equalizing the electro motive force at one terminal connection of each of all the independent circuits, and independently maintaining the currents respectively of said independent circuits each of a practically constant predetermined volume under variations of circuit resistance.

5. The method of operating dynamo electric machines, which consists in subjecting definite fractional parts of the armature coils to individual magnetizing forces constituting the field, and utilizing the electrical energy developed in said different definite fractional parts of the armature by the individual forces to supply difierent and independent circuits, each independent circuit being supplied with energy from a particular one of said individual magnetizing forces, and independently maintaining the currents respectively of said independent circuits each of apractically constant predetermined volume under variations of circuit resistance.

In Witness whereof I hereunto subscribe my name this 18th day of July, A. D. 1894.

FREDERICK I-I. LOVERIDGE. Witnesses:

GEORGE P. BARTON, GEORGE L. ORAec. 

